Extension apparatus for trucks or the like which increase the volume and height of the cargo or bed portion of such a vehicle are known in the art. However, most extension apparatus require removal from the body of the vehicle when not in use and reattachment thereto when in use. This requires much time and effort and often necessitates the presence of special tools. In addition, the extension apparatus often will not be readily available when needed.
To overcome these and many other problems associated with removable extension apparatus, extension apparatus have been designed which remain permanently attached to the body of the truck thereby doing away with the necessity to remove the apparatus when not in use.
An example of such an extension apparatus can be found in U.S. Pat. No. 4,095,838 issued to Arnold Beeler on June 20, 1978. However, the Beeler patent has several problems associated therewith. For example, a flexible fabric is attached between two channel members which in turn are supported in an extended upright, spaced apart relationship by a plurality of horizontally spaced jack-knife support members. The jack-knife support members have a tendency to bind and twist unless the entire extension apparatus is raised substantially simultaneously. Additionally, the jack-knife members are positioned on the outside of the flexible fabric material such that the cargo of the truck box will push the fabric into the jack-knife members thereby causing wear of the fabric.
Furthermore, the positioning of the jack-knife members on the outside of the flexible fabric will often create problems in reaching the extension apparatus during the raising and lowering process. Indeed, it does not appear as though the jack-knife members can be positioned on the inside of the flexible fabric as they will interfere with the fabric material during the folding process when the extension apparatus is lowered.
Additionally, the rectangular open channel-like construction of the upper and lower frame members to which the jack-knife members are attached makes the frame-like members very susceptible to collecting debris such as grain, ice, etc. which might obstruct raising and lowering of the fabric extension.
Furthermore and very importantly, the Beeler extension apparatus does not appear to have the required strength and sturdiness characteristics needed to support such items as roll-up tarp apparatus which are used to enclose the cargo area.
The present invention solves these and many other problems associated with the prior art.